The invention relates to a device for the photometric, in particular spectral photometric, analysis of a liquid sample having the characteristics described in the preamble of claim 1.
Such a device is known from DE 10 2004 023 178 B4. In the known device, a liquid sample is enclosed in a measurement space between a transparent sample carrier and an upper mirror located parallel thereto. Measurement light is radiated through the transparent sample carrier perpendicularly onto the upper mirror so as to analyze the sample. The upper mirror reflects the measurement light beam, so that the measurement light beam passes through the measurement space a total of two times between the light entrance and light exit.
A common method for analyzing liquid samples by way of light is the measurement of the sample absorption at one or more characteristic wavelengths. To this end, an absorption spectrum is generally measured, so as to detect analytes in a sample and determine the concentrations thereof. The level of absorption is the product of the optical path length of the measurement light through the sample, the analyte concentration and an extinction coefficient that is characteristic of the analyte in question at the respective light wavelength. For known extinction coefficients, it is thus possible to calculate a required analyte concentration based on the measured absorption values.
When liquid biological or biochemical samples are analyzed, for example for the quantitative determination of different nucleic acids, proteins or marker dyes, the problem arises that generally only small amounts of samples are available and therefore a quantitative analysis is made difficult.